Movies, videos, and other images may be captured from one or more scenes using a video capture medium such as film or a photodetector array and a video capture device such as a camera or scanner. After processing, the video medium may be used to reproduce the images by displaying the images using a display device. The video medium may also be converted into other formats, e.g. from film into a digital format, for display or additional processing.
A video capture device often captures images with separate color channels, (e.g., red, blue, and green channels). For example, a TechniColor camera captures images using a separate filmstrip for the red, green, and blue colors to generate red, green, and blue frames for each image. Similarly, a color photosensor array found in a digital camera generally includes separate pixels for capturing the red, green, and blue colors of an image.
Unfortunately, many video capture devices do not capture the separate color channels with the same image quality. One or more of the color channels in the video medium may have chromatic aberrations with respect to the one or more of the other color channels. These chromatic aberrations, such as blur, may occur as a result of the properties of either the video capture medium or the video capture device. For example, the red filmstrip in a TechniColor film may be more blurred than the blue and green filmstrips as a result of the light captured on the red filmstrip first passing through the blue filmstrip. As another example, a lens that focuses light onto a photosensor array may have different indices of refraction for different colors. Consequently, one or more of the colors in a photosensor array may be blurred with respect to one or more of the other colors because of properties of the lens.
In addition, the aging characteristics of a video medium may be such that the video medium deteriorates over time or in response to environmental conditions. The deterioration of the video medium may result in misregistration of the color channels of the video medium. Images captured on film using a TechniColor camera provide an example. Since the red, blue, and green color channels are recorded on separate black and white filmstrips with no precision mechanism to align them, there is generally misregistration between the color channels. The misalignment may vary from frame to frame and from shot to shot. This gives a blurred image when the film is projected. Moreover, the filmstrips for each color are developed separately, the chemical process for each filmstrip may result in misregistration of the color channels. In addition, the filmstrips for each color may deteriorate differently or at different rates over time due to such factors as heat and humidity. The deteriorations may lead to warping or shrinking of the filmstrips. As a result, the registration of the displayed images may change over time resulting a color misalignment.
It would be desirable to be able to improve the registration in a digital video.